# A Guide To How A Relay Works

Have you ever wondered how a relay works?

A relay is an electromechanical switch. It works in the same way as a manual switch, but instead of having to manually push the switch, you apply power to it to change the switch position.

This was the first component I learned about and it helped me to start understanding how to electronics works.

It is very useful for turning the power of a device on and off automatically, like I did in this story. And it is also useful for switching higher power devices with a low power.

A relay consists of

• an electromagnet
• a mechanical switch

## Electromagnet

An electromagnet is a simple device made up of a wire wound in a coil around a core of ferromagnetic material such as iron.This is a very interesting device and it is easy to build one yourself.

To create your own electromagnet all you need is a nail and some insulated wire. Wind the wire into a coil around the nail and apply power. Beware, it can get very hot if you have too few windings or too much voltage!

### How it works

When a wire conducts current, it produces a magnetic field. If we wind a wire into a coil around a core of ferromagnetic material such as iron, we magnify this field and we get an electromagnet with enough magnetism to do some interesting stuff.

## Mechanical switch

The relay also consists of a mechanical switch. It may look like this:

By User:Bisgaard, language neutral version by Teslaton (Modification of Image:Relæ3.jpg) [GFDL or CC-BY-SA-3.0], via Wikimedia Commons

When the electromagnet (1) is powered, it will break the initial connection between the middle (3) and the left (2) pin and create a new connection between the middle (3) and the right (4) pin.

On many relays there are at least two switches inside so that you can switch two devices at once.

## Notes of caution

Always check the voltage and current rating of the relay switch. Some are designed for switching only low voltages, while others are meant for switching higher voltages.

I hope this simple guide on how a relay works has helped you to understand how a relay works. Now run along and start soldering some relay circuits!

Return from How A Relay Works to Electronic Components Online